If it helps I was having the same problem with the Tobii Eye Tracker 4C in Prepar3D v4.5. You have to install Tobii Game Hub and then, if when you run the Game Hub it does not detect Prepar3D automatically, you have to browse to the executable file prepar3d.exe for the Game Hub to detect the software. The Tobii Eye Tracker does then work properly and you can fine tune things using the Game Hub settings.